Add an empty set of elements:
elts = doc.addElements()
Add an element in a set of elements:
elts.addElement(element)
Remove an element in a set of elements:
elts.removeElement(element)
Remove all elements in a set of elements:
elts.clearElement()
Access to the elements of the document:
nel = doc.countElements()
elts = doc.getElements(index)
GUI command: Elements